Carrier route record

ASSEA→FLL

Alaska Airlines · Seattle to Fort Lauderdale

Flights: 462
Period: July 2025 to June 2026
Share of route: 56%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.

Alaska on SEA to FLL lands a B+, 4 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 45 minutes on average. That is a workable record, not a spotless one. That rests on 462 flights, with a median arrival 9 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Alaska on SEA to FLL from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

81.4%

Arrivals under 15 minutes late, of 457 completed flights

Avg delay

46 min

Across delayed arrivals only, not all flights

Cancelled

0.43%

National rate is 1.81%

Whole route

78.1%

Every carrier on SEA to FLL, 826 flights

These figures cover 462 flights between July 2025 and June 2026. The median arrival is 9 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Alaska against every carrier on SEA to FLL

Alaska flew 462 of the 826 flights on SEA to FLL, most of the route. Its 81.4% on time is 3 points better than the route as a whole, which runs 78.1%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Alaska at 81.4% to Delta at 73.8%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on SEA to FLL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlines (this page)	462	81.4%	46 min	0.43%	B+
Delta Air Linesthin sample	364	73.8%	53 min	1.65%	C

Flight by flight

Alaska flight numbers on SEA to FLL

AS 51607:5583.4% · 337 flights

Departure window

When Alaska runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 12 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am365 flights83.9%
11am–2pm—
2pm–5pm—
5pm–8pm—
8pm–5am97 flights72.2%

Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 83.9% of the time, against 72.2% for the overnight window. That is 12 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 365 flights scheduled in it.

Across the year

Alaska on SEA to FLL through the year

Darker means more delays. Figures are on-time percentages.May best, December worst

December is the weak month at 67.7% on time, against 93.5% in May. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. December was the busiest month here, with 62 flights.

Across the week, Wednesday is the strongest day at 95.1% on time and Friday the weakest at 73.9%. 21 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

One category carries most of the weight here. National Airspace System accounts for 45% of the 3,881 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
45%
Carrier
38%
Late-arriving aircraft
16%
Extreme weather
1%

45% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 1,758 minutes out of 3,881, against a national NAS share of 21%. The split is drawn from 3,881 reported delay minutes.

The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,478 of the 3,881 delay minutes reported here.

Cancellations are rare at 0.43%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 3.7% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

At 2,717 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.

The return leg is a different operation and performs like one: it runs 66.5% on time across 462 flights, 15 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 15 points of difference.

One caution: this is a thin sample. 462 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Alaska on SEA to FLL

Put together: treat all of this as provisional. 462 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 81.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 457 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures